Premium
A µ‐XANES study of the combined oxidation/sulfidation of Fe–Cr model alloys
Author(s) -
Weber Kathrin,
Guilherme Buzanich Ana,
Radtke Martin,
Reinholz Uwe,
StephanScherb Christiane
Publication year - 2019
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201810644
Subject(s) - xanes , sulfidation , electron microprobe , corrosion , sulfide , oxide , alloy , diffusion , high temperature corrosion , microprobe , materials science , chemistry , analytical chemistry (journal) , lattice diffusion coefficient , metallurgy , inorganic chemistry , spectroscopy , mineralogy , thermodynamics , sulfur , physics , chromatography , quantum mechanics , medicine , radiology , magnetic resonance imaging , effective diffusion coefficient
The precise analysis of cation diffusion profiles through corrosion scales is an important aspect to evaluate corrosion phenomena under multicomponent chemical load, as during high‐temperature corrosion under deposits and salts. The present study shows a comprehensive analysis of cation diffusion profiles by electron microprobe analysis and microbeam X‐ray absorption near edge structure (µ‐XANES) spectroscopy in mixed oxide/sulfide scales grown on Fe–Cr model alloys after exposing them to 0.5% SO 2 . The results presented here correspond to depth‐dependent phase identification of oxides and sulfides in the corrosion scales by µ‐XANES and the description of oxidation‐state‐dependent diffusion profiles. Scales grown on low‐ and high‐alloyed materials show both a well‐pronounced diffusion profile with a high concentration of Fe 3+ at the gas and a high concentration of Fe 2+ at the alloy interface. The distribution of the cations within a close‐packed oxide lattice is strongly influencing the lattice diffusion phenomena due to their different oxidation states and therefore different crystal‐field preference energies. This issue is discussed based on the results obtained by µ‐XANES analysis.